A huge crater in Western Australia was created by an asteroid strike 3 billion years ago, according to a mineral-dating technique. This would make it the oldest impact crater on Earth – but other researchers have questioned its proposed age.

The North Pole Dome crater, also known as the Miralga impact structure, was first described by at Curtin University in Perth, Australia, and his colleagues in 2025. They estimated that it could be up to 100 kilometres wide.

Kirkland and his team found a layer of rock containing cone-shaped features called shatter cones, which form only after a high-impact event, such as an asteroid strike. Their original study didn’t directly date this rock, but based on correlations with dated rocks in the layers above and below, they proposed that the impact .

This would make it more than 1.2 billion years older than the Yarrabubba crater in the south of the state, which is regarded as the oldest reliably dated asteroid-strike crater on Earth.

It would also make it the only known impact from the Archaean aeon, a time when the entire planet was a giant but inhospitable water world.

However, another team, including , also at Curtin University, strongly contested the 3.47-billion-year date. Based on their own analysis of rocks in the area, the team members argue that the impact took place no earlier than .

Free newsletter

Sign up to The Earth Edition

Sign up to newsletter

Now, Kirkland and his colleagues say they have successfully dated recrystallised minerals at the crater site, which contain shatter cones. “We have now actually looked inside the rocks and tried to find minerals that directly responded to impact in the rock itself, rather than making correlations,” says Kirkland.

Using the rate of the decay of uranium into lead, the team dated zircons within the shatter cones, which recrystallised as a result of the force of the asteroid strike.

They also dated the mineral apatite, which would have formed in the hydrothermal system created by the heat of the impact.

Both the apatite and the zircons returned dates of around 3.02 billion years old, says Kirkland. “So now we’ve got evidence for very hot water percolating through the rocks 3 billion years ago and also evidence for this really unusual heating and recrystallisation process,” he says.

Kirkland says no other known process, such as mountain building or regional metamorphism, easily explains the mineral changes inside the shocked rocks, because there is no evidence that the area was heated or deformed by those processes at about 3.02 billion years ago.

“The only process really that we can link to these mineralogical changes is an impact,” he says. “So that means the best evidence now is a 3-billion-year-old impact, and that by far is the oldest impact crater on the planet.”

Cavosie welcomes the fact that the age of the crater has been revised significantly, but he thinks Kirkland’s team is still overestimating the crater’s age.

“While I’m relieved these authors have backed off their 2025 ‘3.5-billion-year impact’ hypothesis, I don’t think they’ve presented a compelling case for a [3.02-billion-year] impact either,” says Cavosie. “The slow march of science towards the truth thus continues.”

Cavosie says there are clearly shatter cones in younger rocks that are only 2.77 billion years old, which means the impact must have happened after this date.

at Yale University, who was also part of the group that critiqued the original study, agrees with Cavosie that the rocks must be younger than 2.77 billion years.

“While the new study dismisses this observation because these rocks ‘have not been dated’, they are straightforwardly correlated to nearby rocks that have been dated,” says Brenner.

Kirkland says the key difference is that his team has now directly dated minerals inside the shocked rocks. “The younger age argument still depends on long-distance correlation of undated rocks, largely from satellite-based mapping rather than direct geochemistry or geochronology,” he says. “We now have two mineral clocks from the impact rocks themselves giving the same age. That is why direct dating matters.”

For decades, geoscientists looked beneath the Earth’s surface as if peering through frosted glass. Today, a revolution in seismic imaging is revealing the structures beneath our feet in unprecedented detail. In this ��è����Ƶ CoLab podcast sponsored by Viridien, meet the geophysicists pioneering these breakthroughs.

Using the data in sound waves reflected from structures up to 20 kilometers deep, these scientists are now creating spectacular 3D images of the Earth’s crust in high resolution.

Watch or listen to this podcast to hear directly from the brilliant minds whose work is transforming how we explore natural resources, locate offshore wind farms and manage energy security on a global scale.

Read More from ��è����Ƶ CoLab: How geophysicists are reverse engineering the Earth

Find out more:

The asteroid strike that wiped out the dinosaurs hit with such force that it took at least 8 million years for the impact site to cool down, creating a warm underground ecosystem where microscopic life thrived.

The Chicxulub asteroid, which collided with Earth 66 million years ago at what is now Mexico, is thought to have been as large as 15 kilometres in diameter. The strike caused so much climate chaos that it wiped out three-quarters of species on Earth. All the dinosaurs except the ancestors of birds became extinct and a nuclear winter gripped the planet for at least 15 years.

Its effects were also felt deep underground. “The Chicxulub impact was big enough to cause deformation at least 35 kilometres under the surface of the Earth, detectable using geophysical surveys,” says at the University of Glasgow, UK.

The impact melted about 10,000 cubic kilometres of rock, she says. The combination of melted rock and seawater created porous material filled with tiny pockets of hot water, known as a hydrothermal system.

Because of the presence of minerals that only form where there is liquid water and heat, we know that the asteroid would have created hydrothermal environments to depths of several kilometres. But the scale and lifespan of the heating and resulting hydrothermal system has, it seems, been massively underestimated.

Previously, it was thought it took only 2 million years for the impact site to cool down. Now, Pickersgill and her colleagues say it may have taken at least four times longer, giving hydrothermal life much more time to thrive.

Free newsletter

Sign up to The Earth Edition

Sign up to newsletter

“One of the biggest unknowns about all impact-generated hydrothermal systems, and Chicxulub in particular, is how long the heat keeps water circulating through the structure,” says Pickersgill.

To figure this out, the team drilled 1 kilometre into the crater to obtain rock cores. Because potassium in the rocks has decayed into argon gas over time, the researchers could measure the amount of argon trapped in the samples to find out their age.

“We got a range of ages from the time of impact at 66 million years ago to about 58 million years ago,” says Pickersgill. “That told us that hydrothermal activity was ongoing in at least part of the Chicxulub structure for 8 million years after the impact.”

Sulphur isotopes in the cores provide evidence that microbial life existed in the hydrothermal system and recovered rapidly after the impact.

The results mean that the very earliest impact craters on the young Earth – and perhaps other worlds – may also have had habitable hydrothermal systems for longer than previously known.

“This provides more opportunity for life to develop, evolve and spread,” says Pickersgill. “It supports the concept that early life on Earth may have found a long-term home in impact craters, and possibly even life on other planets where these massive impact craters are dominant surface features.”

at Curtin University in Perth, Australia, says while there is “not an entirely unambiguous record of continuous hydrothermal activity” at Chicxulub, the evidence is strong that the impact site stayed hot for millions of years.

“Large impacts do not simply destroy environments,” he says. “They can also create long-lived underground systems where hot fluids circulate through shattered rock. These chemically rich settings may provide sheltered habitats for microbes and perhaps even favourable conditions for some of the early chemical steps towards life.”

The African continent may have begun tearing itself apart in a new location. Gases emerging from an arc of hot springs in Zambia appear to be coming from deep below Earth’s crust, in a sign that a new tectonic plate boundary could be opening up.

There are many rift valleys around the world where continents have been pulling apart for tens of millions of years, including the East African Rift valley, which runs from the Red Sea to Mozambique. Over millions of years, rifting can lead to a tectonic plate splitting in two, but it is unusual to find a site where this process may be just beginning, says at the University of Oxford.

The Kafue Rift in Zambia is part of a 2500-kilometre-long rift zone stretching from Tanzania to Namibia and possibly out into the Atlantic Ocean. Geologists think the area may be showing signs of being in the early stages of forming a new boundary between continental plates, because of the geography, low-gravity anomalies, high sub-surface temperatures and low-level seismicity. But, until now, there has been no geochemical evidence.

Karolytė and her colleagues have now analysed gas samples collected from five hot springs and three geothermal wells in central Zambia. The team found that helium and carbon isotope ratios in the gases are the same as those that exist deep beneath Earth’s crust, suggesting that fluids from the mantle, up to 190 kilometres below the springs, are making their way to the surface. This implies a tear in the region’s tectonic plates.

“What our data confirms is that this system is currently ‘awake’ and geologically active,” says Karolytė. “Having an active rift developing doesn’t necessarily mean that in 100 million years you’re going to have an ocean there. But it is a possibility.”

The earliest stages of continental rifting release gases that have accumulated in the rocks for millions of years. Among these is helium, a critical resource for high-tech industry and medicine. In the Kafue Rift, this process has created concentrations of helium of up to 2.3 per cent in the fluids reaching the surface – high enough that the region is already attracting interest from industry.

Free newsletter

Sign up to The Daily

Sign up to newsletter

“It’s hard to find these tectonic conditions that are just right to concentrate and release helium in a way that it can be captured,” says Karolytė.

at the University of Sydney, Australia, says, despite the absence of active volcanoes and significant seismicity, he agrees there are many signs in the region that the landscape is tectonically active.

The new geochemical evidence from the hot springs reveals that the Kafue Rift is an early-stage continental rift where mantle fluids rich in primordial helium-3 are rising through faults, he says. “It is reasonable to think that the Kafue Rift may evolve into a plate boundary sometime in the future.”